Orbiting combustion nozzle engine

ABSTRACT

An orbiting combustor nozzle (OCN) engine, having a rotating assembly comprising a co-rotating compressor and nozzle wheel enclosed within a non-rotating outer casing, defining a rotating combustion chamber, is disclosed. Combustion occurs in the combustion chamber in a vortex of gas that rotates at the same angular velocity as the rotating assembly. Also disclosed, is a method of cooling a blade of a rotating wheel, such as a turbine wheel or nozzle wheel, by projecting cool air at the base of the vane form a nozzle corotating with the blade. Such cooling is easily implemented in an OCN engine with use of an innovative annular combustor. Also disclosed is a method of countering axial backflow by use of a combustion chamber compressor.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to an engine and specifically to an enginehaving a rotating assembly comprising a co-rotating compressor andcompressor-driving nozzle wheel enclosed within a non-rotating outercasing, thus defining a rotating combustion chamber.

In a conventional turbine engine 10, depicted in FIG. 1, one or morenon-rotating combustion chambers 12 are found between a compressor 14and a turbine 16. Compressor rotor 18 and turbine wheel 20 are attachedto a common rotating shaft 22. During operation of engine 10, compressor14 forces air into engine 10 towards combustion chambers 12.Non-rotating terminal stator vanes 24 in compressor 14 direct air athigh pressure into combustion chambers 12 through what is generallycalled a diffuser or diffusion stage. In combustion chambers 12 fuel ismixed with the high pressure air. The fuel-air mixture burns and as aresult of the released heat, the exhaust expands outwards throughturbine 16. In succeeding stages of turbine 16, stationary nozzle guidevanes 30 of turbine 16 accelerate and redirect exhaust gases at rows ofturbine blades 32 of turbine wheel 20. The high velocity exhaust gasesimpact on turbine blades 32 and produce torque on turbine wheel 20 thatrotates shaft 22, driving compressor rotor 18.

One weakness of prior art turbine engines, such as 10 is in the turbine.High efficiency and high power output depends on fast rotation ofturbine wheel 20, achieved by directing high-temperature high-velocitygas jets from between nozzle guide vanes 30 at turbine blades 32. Themechanical and thermal stresses on turbine blades 32 are so high thatengine efficiency is limited by the material properties of turbineblades 32. Thus even though high velocity gas jets can be easilyobtained, these cannot be efficiently utilized due to the shortenedlifetime of the turbine blades. Long-life can be obtained by dilutingexhaust to produce gas jets having only moderate temperature andvelocity and limiting the rate of rotation of the turbine wheel. Thisresults in low efficiency and a limited power output.

A number of turbineless engines been designed overcoming the limitationsimposed by the use of a turbine, see U.S. Pat. Nos. 2,465,856,2,499,863, 2,594,629, 3,200,588, and 6,295,802. All these turbinelessengines have a plurality of combustion chambers, rigidly arrayed about apower shaft having nozzles directed substantially perpendicularly to thepower shaft. Exhaust exiting from the combustion chambers through thenozzles drives the combustion chambers about the power shaft and createstorque in a manner analogous to Hero's Aeolipile. These turbinelessengines have failed to gain popularity, amongst other reasons, due to anexcessive moment of inertia and extreme hoop stress resulting from thepositioning of the combustion chambers.

U.S. Pat. No. 3,557,551 teaches a turbine engine where the velocity atwhich gas emerging from rotating nozzles strikes a turbine is reduced.To this end, a combustion chamber and nozzles are allowed to rotate as aresult of gases escaping through the nozzles. Simultaneously, the gasescaping from the nozzles impacts the turbine blades, turning a turbinewheel in a direction opposite the direction which the combustion chamberand nozzles rotate. Torque is extracted from both rotations. The primarydisadvantage of this design is similar to the disadvantage of theturbineless engines described above: the combustion chambers (termedcombustor baskets) undergo severe hoop stress. An additionaldisadvantage of this design is that air is fed into the combustionchambers using a ram effect and consequently suffers severe aerodynamicentry losses.

A different design, called a rotojet, is taught in “Weight-flow andthrust limitations due to the use of rotating combustors in a turbojetengine” by Lezberg, E. A.; Blackshear, P. L.; and Rayle, W. D. ResearchMemorandum RM E55K16 of the National Advisory Commitee for Aeronautics(1956). In the rotojet, a compressor stage, a turbine and a plurality oframjet-like combustion chambers having off-axis reaction nozzles rotatetogether. Similar to the turbineless engines described above, theindividual combustion chambers (“ramjets”) undergo severe hoop stress.

Another weakness of prior art turbine engines, such as 10 is in thethermodynamics of the engine. Due to the braking of gases exitingcompressor 14 through the non-rotating stator vanes 24 before enteringcombustion chamber 12 and due to the expansion of gases when the gasesexpand through nozzle guide vanes 30 in order to drive turbine wheel 20,there are significant pressure drops and the actual thermodynamic cycleis far from being an ideal Brayton cycle (see Appendix). Thus, prior artturbine engines, such as 10, are inherently inefficient. None of thealternative turbine engines described above presents a solution to theinherent thermodynamic inefficiency of the turbine engine.

In U.S. Pat. No. 6,272,844 and U.S. Pat. No. 6,460,343, one related tothe other, are taught turbine engines without inlet turbine stators toreduce the inlet pressure drop. In these engines a vortex is created inpart of the compressor outlet flow by adding a swirler stator at thecompressor outlet. This solution is inefficient as the air from thecompressor is first diffused at the rotor exit and is again expanded inthe swirler, reducing the pressure even further. Moreover, thecombustion chamber is stationary, creating further pressure drops andvarious stationary envelopes. Moreover, in both U.S. Pat. No. 6,272,844and U.S. Pat. No. 6,460,343, the fact that the combustor is stationarycreates pressure drops due to friction between the vortex and thevarious stationary envelopes.

There is a need for an engine that overcomes the above-listedshortcomings of prior art engines, especially prior art turbine,engines.

SUMMARY OF THE INVENTION

The above and other aims are achieved by the orbiting combustion nozzle(OCN) engine of the present invention.

According to the teaching of the present invention there is provided anengine, comprising: a. a rotating assembly including a primarycompressor, an inner casing and a compressor-driving nozzle wheel; b. anouter casing, enclosing the rotating assembly so that at least onecombustion chamber is defined in the space between the primarycompressor, the inner casing, the compressor-driving nozzle wheel andthe outer casing, the engine characterized in that the outer casing doesnot rotate with the rotating assembly.

According to a feature of the present invention the at least onecombustion chamber is substantially a single annular combustion chamber.

According to a feature of the present invention the engine furthercomprises a combustion chamber compressor in the combustion chamber. Inone embodiment, such a combustion chamber compressor includes aplurality of vanes attached to the inner casing.

According to a feature of the present invention, the rotating assemblyfurther includes a substantially annular flame holder disposed withinthe combustion chamber.

According to a feature of the present invention, the engine furthercomprises a substantially tubular element surrounding the inner casing,wherein a leading edge of the tubular element is positioned aft of theprimary compressor so as to divide airflow from the primary compressorinto an outer airflow and an inner airflow, wherein the outer airflow isbetween the tubular element and the non-rotating outer casing andwherein the inner airflow is between the tubular element and the innercasing. In some embodiments of the present invention, through thesubstantially tubular element are perforations allowing communicationbetween the inner airflow and the outer airflow.

According to a feature of the present invention, the engine furthercomprises a rotating diffuser between the primary compressor and thecombustion chamber. According to a further feature of the presentinvention the rotating diffuser includes extensions to the terminalblades of the primary compressor.

According to a feature of the present invention, the rotating assemblyof an engine of the present invention includes at least one fuelinjector.

In U.S. Pat. No. 6,272,844 and the related U.S. Pat. No. 6,460,343 aretaught engines having no inlet turbine stators. This is done in order toreduce the pressure drop at the turbine entrance. A vortex is created inthe combustion chamber by the use of a swirler stator at the compressoroutlet. This solution is inefficient as air at the compressor outlet hasalready been diffused at the rotor exit. By again expanding the air inthe swirler, the pressure is further reduced.

The present invention avoids analogous pressure losses by substantiallymaintaining an airflow vortex produced by a compressor through arotating combustion chamber and through a nozzle wheel.

Another disadvantage of the teachings of U.S. Pat. No. 6,272,844 andU.S. Pat. No. 6,460,343 is that therein the vortex is generated by aswirler for only for a portion of the compressor airflow. This resultsin a relatively low vortex angular velocity at the turbine inlet,reducing efficiency.

In contrast, according to the teachings of the persent invention, theentire airflow from the compressor makes up the airflow vortex, so thatthe angular velocity of the vortex is substantially similar to theangular velocity of the nozzle wheel.

As still further disadvantage of the teachings of U.S. Pat. No.6,272,844 and U.S. Pat. No. 6,460,343 is that the combustor, beingstationary, creates pressure drops due to vortex/stationary envelopefriction.

In an engine of the present invention under certain operating conditionsan axial backflow can occur. Axial backflow is also known to occur inother engines, for example in gas turbine engines where swirls aregenerated to increase air/fuel mixing efficiency. When axial backflowoccurs, hot air from the aft section of the combustor flows forwards. Tocounter axial backflow, there is also provided according to theteachings of the present invention an engine comprising: a a combustionchamber having an axis; and b. a combustion chamber compressor, coaxialwith and radially inwards from the combustion chamber, the combustionchamber compressor configured to counteract axial backflow in thecombustion chamber.

According to a feature of the present invention the combustion chambercompressor includes: c. at least one combustion chamber compressor bladearrayed about the axis of the combustion chamber in at least one circle;and d. a substantially tubular combustion chamber compressor bodyencasing the combustion chamber compressor blades.

According to a feature of the present invention the combustion chambercompressor includes: c. a rotating combustion chamber inner casingcoaxial with the combustion chamber; d. at least two combustion chambercompressor blades rigidly attached to the rotating combustion chamberinner casing and arrayed about the axis of the combustion chamber in atleast one circle; and e. a substantially tubular combustion chambercompressor body encasing the combustion chamber compressor blades.

According to a feature of the present invention the combustion chambercompressor blades are arrayed in one or more circles about the axis(preferably symmetrically within each circle) where each circle includesat least two, preferably more than two blades.

Combustion engines, especially those operating at high temperatures,often produce undesirably large quantities of polluting NO_(x)emissions. One method of reducing such emissions is to reduce the oxygencontent of the combustion mixture by mixing exhaust into the combustionmixture, a process known in the art as exhaust reinjection. Thepreferred method of exhaust reinjection for an engine of the presentinvention uses the fact that there exists a radial pressure gradient inthe engine, where there is a lower static pressure closer to the axisthen further from the engine axis. Thus, there is also providedaccording to the teachings of the present invention in an engine havinga combustion chamber wherein a mixture of fuel and air is burned, amethod of reducing NO_(x) emissions by: a making a combustible mixtureby combining exhausts fuel and air in a first region of the engine; andb. burning the combustible mixture in the combustion chamber; whereinthe exhaust is taken from a second region of the engine that has ahigher static pressure than that of the first region.

Turbines blades of turbine engines are exposed to high centrifugalstress and as a result often break at the base due to creep at hightemperatures. The preferred prior art method of injecting a coolingfluid through turbine blades fashioned with special cooling channels isexpensive. Centrifugal stress is also a problem to which the nozzlewheel of an engine of the present invention is subject and in fact ageneral problem encountered in other devices having a rotating wheelwith blades herein referred to as a bladed rotating wheel). Thus, thereis also provided according to the teachings of the present invention amethod of cooling a blade of a bladed rotating wheel attached to theterminal end of a rotating axis through a blade base, by: a providing atleast one substantially axial channel rotating with the rotating axis,the at least one channel having an inlet and an outlet; b. feeding acooling fluid into the the channel through the inlet; and c. directingthe cooling fluid emerging from the channel through the outlet at theblade base to be cooled.

In order to increase cooling efficiency especially in cases where thepressure at the inlet is too low to ensure a sufficient flow of coolingfluid from the outlet, the pressure of the cooling liquid emergingthrough the outlet is increased by using a pressure-increasing devicepositioned inside the channel, for example a combustion chambercompressor as described hereinabove. According to a feature of thepresent invention, the bladed rotating wheel is a nozzle wheel or aturbine, and the blade is a nozzle wheel blade or a turbine blade,respectively.

According to a feature of the present invention, centrifugal forces areused to tranport cooling fluid emerging from the outlet along a leadingedge of the blade being cooled.

U.S. Pat. No. 6,272,844 teaches a method of turbine blade cooling inwhich a rotating bladed disc is attached to a rotating turbine wheel.The effect is that a portion of the cool air from the compressor istransported through a passages to emerge in front of a respectiveturbine blade. The cool air envelopes and cools the respective turbineblade. Despite a superficial similarity to the present invention, it ishighly doubtful that the teachings of U.S. Pat. No. 6,272,844 shallfunction as described.

The primary problem with such a solution problem is that air enteringthe inlets of the passages (designated 40 in U.S. Pat. No. 6,272,844) isunable to flow through the passages and emerge through the coolingoutlets (designated 44 in U.S. Pat. No. 6,272,844). This is a result ofthe fact that since the air at the inlet is not centrifuged, the staticpressure in the vicinity of the inlets is lower than the static pressurein the outlets. In fact, under such conditions hot air will flowradially from the periphery of the turbine towards the axis heating,rather than cooling, the turbine blades.

There is also provided according to the teachings of the presentinvention a method of producing torque by: a) providing a vortex of afluid rotating at a first angular velocity about an axis; b) directingfluid from the vortex through at least one nozzle, the nozzle rotatingon a shaft at a second angular velocity about the axis; and c)extracting the torque from the shaft.

According to a feature of the present invention, the first angularvelocity and the second angular velocity are substantially equal.According to a further feature of the present invention the vortex isenclosed within a non-rotating outer casing.

There is also provided according to the teachings of the presentinvention a method of producing torque by: a. generating a vortex ofcompressed air rotating at a first angular velocity about an axis; b.mixing a combustible fuel with the compressed air; c. burning the fuelwithin the vortex; d. directing air heated by the burning from thevortex through at least one nozzle, the nozzle rotating on a shaft at asecond angular velocity about the axis; and e. extracting the torquefrom the shaft.

According to a feature of the present invention, the first angularvelocity and the second angular velocity are substantially equal.According to a further feature of the present invention the vortex ofair is enclosed within a non-rotating outer casing. According to a stillfurther feature of the present invention, the vortex is generated by acompressor rotating about the vortex axis at the second angularvelocity.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings, wherein:

FIG. 1 (prior art) is a largely cross-sectional depiction of aconventional turbine engine;

FIG. 2 is a largely cross-sectional depiction of a turbojet embodimentof an OCN engine of the present invention having rotating fuel injectorsthat are part of the flame holders;

FIG. 2A is largely cross-sectional depiction of the combustion chamberof a turbojet embodiment of an OCN engine of the present invention;

FIG. 2B is a longitudinal section of a rotating assembly of anembodiment of an OCN engine;

FIG. 3 is a largely cross-sectional depiction of a combustion chamber ofan OCN engine having static fuel injectors located at thediffuser/combustion chamber interface;

FIG. 4 is a largely cross-sectional depiction of a combustion chamber ofan OCN engine with an annular flame holder and exhaust reinjection;

FIG. 5 is a transverse cross-section of an OCN engine depicting acombustion chamber compressor;

FIG. 6A is an axial cross section of a compressor-driving nozzle wheeldepicting three nozzle wheel blades, two nozzles and an implementationof the blade cooling method of the present invention;

FIG. 6B depicts, in cross section in a cylindrical plane that is coaxialwith the axis of an OCN engine, details of the cooling of the base of ablade of a compressor-driving nozzle wheel according to the method ofthe present invention;

FIG. 7 is a largely cross-sectional depiction of an embodiment of aturboshaft embodiment of an OCN engine having a free-nozzle wheel todrive the load;

FIG. 8 is a perspective view of a schematic depiction of a rotatingassembly of an OCN engine configured for partial admission;

FIG. 9 is a largely cross-sectional depiction of an embodiment of aturbofan embodiment of an OCN engine; and

FIG. 10 is a largely cross-sectional depiction of an embodiment of aturboprop embodiment of an OCN engine.

DETAILED DESCRIPTION OF THE INVENTION

The engine of the present invention is characterized in having arotating assembly comprising a co-rotating compressor and nozzle wheelenclosed within a non-rotating outer casing, thus defining a rotatingcombustion chamber. Since, in contrast to prior art turbines, in theengine of the present invention there is no turbine wheel and torque isgenerated using a rotating nozzle wheel, and because combustion occursin a vortex of air rotating together with the rotating assembly, theengine of the present invention is called an orbiting combustion nozzle(OCN) engine.

The principles and operation of an OCN engine according to the presentinvention may be better understood with reference to the drawings andthe accompanying description. In the drawings, like references designateequivalent parts

A typical, non-limiting, embodiment of an OCN engine 40 is schematicallydepicted in FIG. 2. This depiction, and other depictions below, areprimarily in cross section. It will be clear in the following discussionwhich depicted elements (for example air slots 82) are not depicted incross section. OCN engine 40 is analogous to a prior art turbojet enginesuch as turbine engine 10 depicted in FIG. 1. As with prior art turbineengines, OCN engine 40 has a compressor 42 and a combustion chamber 46.However, unlike turbine engine 10 where non-rotating terminal statorvanes 24 direct compressed air from compressor 14 to combustion chambers12, in an OCN engine such as 40 air is directed from compressor 42 tocombustion chamber 46 by rotating diffuser blades 44. Further, unlikecombustion chamber 12 of of turbine engine 10, combustion chamber 46 ofOCN engine 40 is a rotating combustion chamber. Combustion chamber 46 ofOCN engine 40 is depicted in detail in FIG. 2A. Further, instead of aturbine 16, torque to drive compressor 42 is produced in torque-section48 using a compressor-driving nozzle wheel 50.

Defining the axis of engine 40 is rotating shaft 52. OCN engine 40 has arotating assembly 54 (see FIG. 2B) including rotating shaft 52 to whichare connected axial stage compressor rotors 64, compressor impeller 68,flame holders 58, inner casing 60 and compressor-driving nozzle wheel50. In some embodiments of an OCN engine, some elements of rotatingassembly 54 are not directly attached to rotating shaft 52, but ratherindirectly attached, for example, through inner casing 60.Significantly, during operation of OCN engine 40, all parts of rotatingassembly 54 rotate with the same angular velocity about the axis ofengine 40. In some embodiments of an OCN engine other engine componentsare also part of a corresponding rotating assembly. Rotating assembly 54is encased in a non-rotating outer casing 62. It is important to notethat the inner surface of stationary outer casing 62 is considered as apart of combustion chamber 46.

Compressor

Just as a prior art turbine engine such as 10, an OCN engine made inaccordance with the teachings of the present invention has a compressor.A compressor of an OCN engine is substantially similar to prior artcompressors and is of any type commonly used in turbine engines, such asa centrifugal flow compressor, an axial-flow compressor or a dualaxial-centrifugal-flow compressor. The advantages of the variouscompressor configurations are well-known to one skilled in the art andneeds not be discussed hereinfurther.

An important difference, however, between compressors of prior artturbine engines such as 10 and compressor 42 of an OCN engine is that inan OCN engine there is no static stator 24. This lack is discussedhereinbelow in the section relating to the diffuser.

OCN engine 40 in FIGS. 2 is equipped with a dual axial-centrifugalcompressor 42 having two axial compressor rotors 64, stator vanes 66 anda centrifugal impeller 68.

It is important to note that in some embodiments of the presentinvention, an engine is equipped with more than one compressor.Therefore, in some cases a compressor, such as 42 of OCN engine 40 isreferred to as a primary compressor.

Rotating Diffuser

Prior art turbine engines such as 10 have an axial air flow throughcombustion chambers 12. The function of non-rotating terminal statorvanes 24 making up a stationary diffuser stage is to receive air fromcompressor rotor 14, axialize the airflow and convert velocity to staticpressure. In a prior art turbine engines such as 10 air typically entersthe diffusion stage with a velocity of 400 m/sec and is slowed down bydiffusion and the effect of non-rotating terminal stator vanes 24 to avelocity of about 70 m/sec. This braking leads to a 5%-10% loss incompressor efficiency.

In contrast, in an OCN engine air entering the combustion chamber travelin a vortex about the engine axis. Accordingly, an OCN engine does nothave a stationary diffuser stage but a rotating diffuser stage. In anOCN engine the rotating diffuser directs the air flow exiting thecompressor towards the combustion chamber and converts relative velocityto static pressure. However, the airflow vortex is not damped, but israther preferably enhanced.

In a most simple embodiment, the diffuser stage of an OCN enginesubstantially includes rotating diffuser blades as extensions of theblades of the terminal compressor rotor or impeller. The shape of thechamber wherein the diffuser blades rotate is such that rotation of thevortex of air exiting a corresponding compressor impeller is directed,as a vortex, towards the combustion chamber. Further, due to thereduction in airflow velocity that occurs from the impeller through thediffuser, the static pressure of the airflow is increased while therotational momentum of the gas vortex is conserved or even enhanced. Asthe velocity of the air in an OCN engine is measured relative torotating parts, the velocity reduction is low, for example from about200 m/sec (relative velocity) to 100 m/sec due to decelaration throughthe diffuser, leading to a mere 2% loss of compressor efficiency.

As depicted in FIG. 2 and in FIG. 2 b, rotating diffuser blades 44 ofOCN engine 40 are simply physical extensions of the blades ofcentrifugal impeller 68. Rotating diffuser blades 44 enhance therotational momentum of the gas vortex entering rotating combustionchamber 46 of engine 40.

Rotating Combustion Chamber

There exist many combustion chamber configurations for prior art turbineengines. In an OCN engine, the combustion chamber is substantially avortex-flow annular type combustion chamber where the gases travel in avortex about the central axis of the engine itself. However, since thegas vortex rotates with substantially the same angular velocity as thecompressor, the diffuser and the compressor-driving nozzle wheel, in therotating assembly frame of reference the combustion chamber is anaxial-flow type combustion chamber, in which the swirl velocity isrelatively low (expected to be typically about 80 m/sec).

Structurally a combustion chamber of an OCN engine, for examplecombustion chamber 46 of OCN engine 40 depicted in FIG. 2A, issubstantially a single annular chamber defined by rotating assembly 54and the inner surface of non-rotating outer casing 62.

During operation of OCN engine 40, air propelled by rotating diffuserblades 44 is mixed with fuel from rotating injectors 74 making up partof rotating flame holders 58. A primary zone for combustion is createdby rotating flame holders 58, generating a homogenous annular flame.

Placement of Fuel Injectors

A first preferred location to place fuel injectors in an OCN engine istogether with or in the proximity of the flame holders, as depicted inFIGS. 2, 2A and 2B where rotating injectors 74 of OCN engine 40 are partof rotating flame holders 58.

A second preferred location to place fuel injectors in an OCN engine isin the area where the air flow vortex exits the rotating diff-user intothe combustion chamber, as depicted in FIG. 3 for combustion chamber 47.The vortex at the diffuser/combustion chamber interface is an effectivepre-mix zone allowing the creation of a homogenous fuel/air mixture.Such homogenous dispersion allows for the combustion of lean mixtureswith relatively low NO_(x) emission.

Rotating Fuel Injectors

In OCN engine 40 depicted in FIGS. 2, 2A and 2B fuel is directed throughfuel channels 76 running through rotating shaft 52 to rotating injectors74, emerging into combustion chamber 46 through rotating flame holders58. OCN engines equipped with rotating injectors are generally morecompact than OCN engines equipped with static injectors. Also, whenrotating injectors are used, high-pressure fuel pumps are unneccessaryas fuel is sprayed from the injectors by centrifugal force.

Static Fuel Injectors

Although OCN engine 40 depicted in FIGS. 2, 2A and 2B is depicted ashaving rotating injectors 74, an OCN engine can instead be equipped withstatic fuel injectors 74 b, as depicted in FIG. 3.

In FIG. 3 is depicted a combustion chamber 47 of an OCN engine similarto combustion chamber 46 depicted in FIG. 2A, one significant differencebeing that rotating fuel injectors are replaced with static fuelinjectors 74 b. Static injectors 74 b emerge into combustion chamber 47at the diffuser/combustion chamber interface.

The mixing of air with fuel injected through static injectors 74 b ismore efficient than the mixing of air with fuel injected throughrotating injectors 74 due to the airflow vortex inside combustionchamber relative to the static injectors 74 b. Thus static injectorssuch as 74 b are preferred for use in static OCN engines having largecombustion chambers.

Rotating Flame Holders

In OCN engine 40 depicted in FIGS. 2, 2A and 2B as well as in combustionchamber 47 depicted in FIG. 3, primary zones are generated usingrotating flame holders 58. Rotating flame holders 58 are considered partof rotating assembly 54. In some embodiments of OCN engines primaryzones are generated using non-rotating flame holders (not depicted)attached to outer casing 62. The design and placement of rotatingflameholders 58 or non-rotating flame holders is known to one skilled inthe art. It is noteworthy that the use of flame holders is unusual incombustion chambers of turbine engines and is typically found only inramjet engines or in the afterburner of a prior art turbine engine.

In a preferred embodiment of an OCN engine, an annular flame holder isused. The annular flame holder is described in detail hereinbelow.

Dilution and Thermal Insulation

In an OCN engine, a preferred method of exhaust gas dilution is by airinjected into the combustion chamber through the inner casing or throughboth the the inner casing and through the outer casing.

In combustion chambers 46 depicted in FIGS. 2A and 47 depicted in FIG.3, a certain proportion of air from compressor 42 is brought throughcooling channels such as 78 to emerge into combustion chamber 46 throughinner casing air slots 80.

In FIG. 2A, cooling channel 78 is one of a plurality of cooling channelsthrough inner casing 60 bringing cool air from compressor 42.

In contrast, cooling channel 78 of combustion chamber 47 depicted inFIG. 3 is defined by a space formed between inner casing 60 and atubular element 79. Tubular element 79 is disposed surrounding andcoaxial with inner casing 60, and is rigidly connected thereto by fourrings of struts 86 a, 86 b, 86 c and 86 d. Struts 86 a, 86 b, 86 c and86 d are positioned so as to define, together with tubular element 79, a“combustion chamber compressor” discussed in detail hereinbelow.

The advantage of dilution air injected through inner casing air slots 80is twofold. First, since inner casing air slots 80 are rotating, airinjected therethrough has angular momentum and thus does not disturb theair flow vortex. Second, the colder, and thus denser air, injectedthrough inner casing air slots 80 is carried outwards by centrifugalforces towards outer casing 62. Dilution air is effectively mixed withexhaust.

Outer Casing

As noted in the introduction hereinabove, prior art turbine engines withrotating combustion chambers have rotating outer casings. The result isthat the outer casing of such prior art turbine engines are subject tohigh hoop stresses that ultimately limit the maximal attainablerotational velocity, curtailing power output. In contrast an OCN enginedoes not have outer casing hoop stress. A disadvantage of the fact thatthe outer casing of an OCN engine does not rotate with the airflowvortex so there is flow friction typically leading to an about 2% dropin pressure in the air flow vortex. Flow friction can be reduced in anOCN engine by injecting air into the combustion chamber through openingsin the outer casing to change the flow at the air flow vortex/outercasing boundary to turbulent flow. In addition, air injected through theouter casing assists in maintaining a thermally insulating air blanket.Still further, air injected through the outer casing dilutes exhaustgases.

In combustion chambers 46 depicted in FIGS. 2A and 47 depicted in FIG.3, air is injected through outer casing air slots 82 in outer casing 62.As discussed above, such injection, reduces flow friction between theair flow vortex and the outer casing, assists in the maintenance of athermally insulating air blanket to protect outer casing and dilutesexhaust gases.

In combustion chamber 47 depicted in FIG. 3, it is seen that the shapeof the inner surface of outer casing 62, defining the outer boundary ofcombustion chamber 46 is, in cross section, convex outward. The convexoutward cross section is effective in trapping cool air injected throughinner casing air slots 80 that is brought by centrifugal forces to outercasing 62. In such a way, a self-replenishing thermally insulating airblanket is formed in order to prevent overheating of outer casing 62.

Inner Casing with Annular Flame Holder

In FIG. 4 is depicted a combustion chamber 49 of an OCN engine similarto combustion chamber 46 of OCN engine 40 depicted in FIG. 2A. Onesignificant difference is that rotating flame holder 58, coolingchannels 78 and inner casing slots 80 of combustion chamber 46 depictedin FIG. 2A are replaced with an annular flame holder 84 in combustionchamber 49. Annular flame holder 84 (hatched) combines the functions ofa flame holder and dilution effecting element in a one structurallysimple yet highly effective component. In addition, annular flame holder84 allows for effective cooling of compressor driving nozzle wheel 50,as discussed in detail hereinbelow. Annular flame holder 84 issubstantially a tubular structure attached to inner casing 60 by aplurality of struts 86. The leading edge 88 of annular flame holder 84is aerodynamic so as not to cause turbulence or shock waves in theairflow vortex. From leading edge 88 the cross-section of annular flameholder 84 comprises a first leg 90 which ends at a step 92. From step 92the cross-section of annular flame holder 84 continues with a second leg94. In short, the cross-section of annular flame holder 84 is roughly aharpoon or Z-shape.

The presence of annular flame holder 84 in the airflow vortex dividesairflow into two different airflows, a first outer airflow betweenannular flame holder 84 and outer casing 62 and a second inner airflowbetween annular flame holder 84 and inner casing 60. Although the idealratio of air flow diverted to the inner airflow and outer airflow isdependent on many factors, it is currently believed that between 25% and35% of the total airflow is preferably directed to the outer airflow.

The presence of step 92 in annular flame holder 84 in the airflowgenerates a volume of air that is relatively slow moving in the axialdirection and consequently acts as a primary zone in combustion chamber46.

Disposed through annular flame holder 84 are a plurality of passages orperforations 96 configured so as to allow air to pass from the innerairflow through annular flame holder 84 and to merge with the outerairflow, especially in the primary zone and in the dilution zones. Thesize, shape and distribution of passages or perforations 96 is chosen soas to allow efficient cooling of annular flame holder 84 as well as toallow efficient mixing and dilution of the primary and secondary zonesduring combustion. In a preferred embodiment, not all of the innerairflow is allowed to merge with the outer airflow through annular flameholder 84 but rather a significant portion is allowed to pass beyond theaft end of annular flame holder 84 for effective cooling of compressordriving nozzle wheel 50, as discussed in detail hereinbelow.

Specifically, depicted in FIG. 4 are two types of perforations throughannular flame holder 84.

The first type of perforations, 96 a and 96 b are of a size, shape anddirection through annular flame holder 84 so as to leak air from innerairflow substantially parallel to second leg 94. In such a way, secondleg 94 is insulated from heat generated by fuel combustion in theprimary zone by a film of air flowing through perforations 96 a and 96b.

The second type of perforations, 96 c and 96 d are of a size, shape anddirection through annular flame holder 84 so as to leak air from theinner airflow to both dilute the outer airflow and to form a thermallyinsulating film of cool air in contact with and flowing in parallel tosecond leg 94. Importantly, the location of perforations 96 c and 96 dis such that the dense cool air from inner airflow, that does not mixwith air from outer airflow, is carried by centrifugal forces to theinner surface of outer casing 62. In such a way, a continuouslyreplenished insulating cold air layer is formed along the inner surfaceof outer casing 62, as discussed hereinabove for combustion chamber 46depicted in FIG. 2A.

One skilled in the art recognizes that when using an annular flameholder as described hereinabove the thermal gradient generatedperpendicular to the engine axis is close to ideal. In proximity tomechanical structure, that is annular flame holder 84 and outer casing62, the air is relatively cool. In contrast, in the center of theprimary zone the air is hot

Struts 86 are radially arranged in sets, each set arrayed as a ring ofsubstantially parallel struts about inner casing 60. Struts 86preferably have an airfoil shape to minimize pressure losses. Struts 86serve four primary purposes.

The first primary purpose of struts 86 is structural, to hold annularflame holder 84 in place.

The second primary purpose of struts 86 is to generate an insulatingblanket of cool air to prevent migration of the flame from the primaryzone to inner casing 60.

In an OCN engine, the airflow vortex generates a radial static pressuregradient inside the combustion chamber that increases towards the outercasing. One effect of this gradient is that under certain conditionsthere is a back flow of hot exhaust air from the proximity ofcompressor-driving nozzle wheel, along the inner casing, towards thefront of the engine. Thus, the third primary purpose of struts 86 is toprevent back flow, resulting from the airflow vortex in an OCN engine,from compressor-driving nozzle wheel 50 along inner casing 60. Apreferred method of achieving this is that some of struts 86 are angledin such a way so as to substantially define a compressor in combustionchamber 49. This combustion chamber compressor increases the pressure ofthe inner air flow, preventing backflow from compressor-driving nozzlewheel 50.

The fourth primary purpose of struts 86, related to the third primarypurpose, is to increase the pressure of the inner airflow so as toimprove the dilution of the primary zone. Although dilution from theinner airflow is assisted by centrifugal forces and the greater densityof the cool air making up inner airflow, dilution is even more effectiveas a result of the combustion chamber compressor.

In combustion chamber 49 of an OCN engine depicted in FIG. 4, struts 86are arranged in four rings. Struts 86 a of the first ring are vaneshaped and positioned at an angle of from about 30° to about 50° fromparallel with the engine axis. Struts 86 b of the second ring are vaneshaped and positioned at an angle of about 10° to about 20° fromparallel with the engine axis. Thus, struts 86 a and 86 b implement theconcept of the combustion chamber compressor. Struts 86 c of the thirdring and struts 86 d of the fourth ring, having primarily a structuralfunction, are vane shaped and substantially parallel to the engine axis.

In FIG. 5 a transverse cross-section perpendicular to the axis ofcombustion chamber 49 through struts 86 b, also depicted in FIG. 4. Itis seen that struts 86 b attach annular flame holder 84 to inner casing60. Further it is seen that struts 86 b are positioned at an angle fromthe axis of the engine. In such a way, inner casing 60, struts 86 b andannular flame holder 84 define a combustion chamber compressor.

One skilled in the art recognizes that engine types other than OCNengines may also suffer from axial backflow. It will be clear to oneskilled in the art, upon reading the description of a combustion chambercompressor hereinabove, how to overcome the difficulties caused by axialbackflow in other types of engine by implementing, with the appropriatemodifications, the teachings herein.

A design issue that must be addressed when implementing an annular flameholder, such as 84, in an OCN engine is the hoop stress to which anannular flame holder is subject. First, it is important to remember thatthe small radius of an annular flame holder means that hoop stresses areinherently low. Further, since an annular flame holder is generally asmall-one piece component supported by radial struts to an inner casing,problems associated with hoop stresses can be avoided at reasonable costby fashioning the annular flame holder robustly and from rigid materialssuch as super alloy metals or ceramic materials.

Exhaust Reinjection

In the art, the reinjection of exhaust gases into the primary zone toreduce oxygen content and consequently NO_(x) emissions is well known.In an OCN engine, exhaust reinjection is simple to achieve due to thefact that the radial static pressure gradient inside the combustionchamber increases towards the outer casing.

In FIG. 4 exhaust reinjection is depicted for an OCN engine. Exhaustreinjection inlet 77 in outer casing 62 is found upstream ofcompressor-driving nozzle wheel 50. Exhaust reinjection outlet 79 isfound in proximity of the primary zone generated by annular flame holder84, and preferably as close as possible to inner casing 60. Exhaustreinjection outlet 79 and exhaust reinjection inlet 77 are incommunication through exhaust reinjection pipe 81 allowing the flow ofgases from exhaust reinjection inlet 77 to exhaust reinjection outlet79. The part of exhaust reinjection pipe 81 that extends into combustionchamber 46 has an aerodynamic shape so as not to cause turbulence in theairflow vortex inside combustion chamber 46. Exhaust reinjection pipe 81passes through valve 83, valve 83 configured to regulate exhaustreinjection if desired.

When it is desired to perform exhaust reinjection, valve 83 is opened.Due to the fact that exhaust reinjection inlet 77 is far from the engineaxis where static pressure is high whereas exhaust reinjection outet 79is close to the engine axis where static pressure is low, oxygen-poorexhaust flows through exhaust reinjection pipe 81 into the primary zoneof combustion chamber 46.

Torque Section: Compressor-Driving Nozzle Wheel

Turbines of prior art turbine engines, such as 10, comprise one or morestages. Each stage comprises a non-rotating nozzle wheel having aplurality of radially disposed nozzle guide vanes 30 and a turbine wheel20 having radially disposed turbine blades 32. Nozzle guide vanes 30direct air flowing emerging from combustion chambers 12 at an acuteangle, typically in the range of 25° to 35° from parallel with theengine axis. Turbine blades 12 have an impulse, reaction orimpulse-reaction airfoil cross-section. Although these cross-sectionsare necessary for efficient turbine operation, a significant amount ofenergy is lost due to suction generated on one face of the airfoil andpressure generated on the other face of the airfoil resulting insecondary flows between any two adjacent blades. More significantly, thecross-section of the turbine blade necessitates that the airflow alongthe vanes be subsonic to prevent the generation of supersonic shockwaves at the leading and trailing edges. The requirement for subsonicflow limits turbine pressure ratio and increases engine complexity whenmultistage turbines are required. For example, in a typical prior artturbine engine having 25 bar pressure in the combustion chamber, eachstage of the turbine must have a pressure ratio limit of about 2.5-3.0in order to avoid supersonic flow. Such a typical engine must thereforehave 3 stators and 3 turbines with the inherent high complexity andconcomitant expense.

In contrast, an OCN engine such as OCN engine 40 depicted in FIG. 2 hasneither a turbine wheel nor a non-rotating nozzle wheel, but rather acompressor-driving nozzle wheel 50 that is part of rotating assembly 54.Compressor-driving nozzle wheel 50 is substantially a plurality ofnozzle wheel blades 98 radiating outwards from a hub attached torotating shaft 52. FIG. 6A is an axial cross section of acompressor-driving nozzle wheel 50 depicting three blades 98 and twonozzles 102. As is seen in FIG. 6A, the space between two adjacentnozzle wheel blades 98 defines a nozzle 102. Nozzle 102 preferably has aconverging-diverging shape.

Since in an OCN engine, such as OCN engine 40, produces torque without aturbine, the exit angle of nozzles 104 can be virtually any anglebetween close to 0° (parallel to the engine axis) or close to 90°(perpendicular to the engine axis). As is clear to one skilled in theart, when it is desired to produce more thrust, the exit angle ofnozzles 104 is generally smaller (closer to parallel to the engine axis)so that the velocity of gas jets emerging from nozzles 104 have asignificant axial component. In contrast, when it is desired to producemore torque, the exit angle of nozzles 104 is preferably greater (closerto perpendicular to the engine axis) and, in principle, can be as closeas possible to perpendicular to the engine axis. In such a way, amaximal amount of torque is produced.

In FIG. 6A, nozzle wheel blades 98 are positioned so that the exit angleof gas jets exiting nozzles 102 is 82° from parallel with the engineaxis (the drawing is exagerrated for clarity).

During OCN engine operation, the airflow vortex rotates together withcompressor-driving nozzle wheel 50 and nozzle wheel blades 98 andexpands through nozzles 102. The gas accelerates to an exit velocitywhich depends on compressor-driving nozzle wheel 50 back pressure. Dueto the converging-diverging shape of nozzle 102 the velocity may besupersonic in the relative flow while the absolute exit velocity remainssubsonic. In such a way pressure losses are minimized while expansionefficencies are maximized.

Cooling of Compressor-Driving Nozzle Wheel

One of the weak points of a prior art turbine engines, such as 10, isthat due to the extreme thermal and mechanical stresses, turbine bladesoften break at the base. One preferred solution to reduce turbine bladestress involves passing cool air through cooling channels running insidethe blades and emerging through pores on the blade surface. Such cooledturbine blades increase the complexity and cost of a turbine engine, aswell as reduce net turbine efficiency due to the air which cools theblades but is not used for expansion through the turbine.

In U.S. Pat. No. 6,272,844 a method of cooling turbine blades is taughtwhereby a rotating bladed disk attached to a rotating turbinecentrifugally pushes air from a compressor through multiple passagesfacing each turbine blade, enveloping each blade with cool air.

In an OCN engine, due to the fact that nozzle wheel blades are rotatingtogether with the inner casing as part of the rotating assembly,efficient cooling of nozzle wheel blades can be achieved, as describedhereinbelow.

In the OCN engine depicted in FIG. 3, air to cool nozzle wheel blades 98is brought to blade cooling nozzles 104 through cooling channels 78. InOCN engines having an annular flame holder, such as depicted in FIG. 4,air to cool nozzle wheel blades 98 is brought to blade cooling nozzles104 by directing a part of the inner-air flow to blade cooling nozzles104.

In FIG. 3 and FIG. 4, cool air emerges from each blade cooling nozzle104 directly at the base of a corresponding nozzle wheel blade 98, asdepicted in FIG. 6A and FIG. 6B. FIG. 6B shows further details of thecooling of the base of a blade 98 of a compressor-driving nozzle wheel50 according to the method of the present invention in cross section ina cylindrical plane that is coaxial with the axis of an OCN engine.

Beyond just cooling the base of a corresponding nozzle wheel blade 98,the dense cool air emerging from blade cooling nozzles 104 is carried bycentrifugal forces as a film along nozzle wheel blade 98, giving acooling effect along a significant length of nozzle wheel blade 98.Thus, whereas in prior art cooled turbine blades cooling efficacy islimited by factors such as flow through the cooling passages, porelocation and geometry, blade cooling as described hereinabove creates aninsulating blanket of air starting at the hottest part of a blade, theleading edge. In addition, when blade cooling is performed according tothe teachings of the present invention, the cooling air is not heated asit passes through the turbine disk and the cooling passages, as occurswhen prior art cooled turbine blades are used.

As discussed previously, one skilled in the art recognizes that undercertain OCN engine operating conditions the airflow vortex generates anaxial pressure gradient sufficient to cause backflow from the proximityof torque-section 48 along the surface of inner casing 60. In combustionchambers such as 47 depicted in FIG. 3 or 49 depicted in FIG. 4, suchbackflow reduces the efficacy of cooling by preventing cool air fromemerging through cooling nozzles 104. It is thus necessary to increasethe pressure of air emerging through cooling nozzles 104. To this end, acombustion chamber compressor is provided.

In combustion chamber 49 depicted in FIG. 4 struts 86 a and 86 b arepositioned in a manner, as discussed above, so that together withannular flame holder 84 a combustion chamber compressor exists. Rotationof inner casing 60 as part of rotating assembly 54 also causes therotation of struts 86 a and 86 b as well as annular flame holder 84,increasing the pressure of the inner air flow and the pressure of airemerging through blade cooling nozzles 104.

Analogously, in combustion chamber 47 depicted in FIG. 3 struts 86 a and86 b are positioned in the manner discussed above, so that struts 86 aand 86 b together with tubular element 79 and inner casing 60 define acombustion chamber compressor. Rotation of inner casing 60 as part ofrotating assembly 54 also causes the rotation of struts 86 a, 86 b andtubular element 79, increasing the pressure of the air emerging throughblade cooling nozzles 104.

It is clear that the cooling of a nozzle wheel blade as described allowsthe operating temperature of an OCN engine to be significantly higherthen prior art engine turbine engine designs. Higher operatingtemperatures allows greater engine efficiency.

One skilled in the art realizes that the cooling OCN engine nozzle wheelblades as taught herein can be implemented, with appropriatemodification, to prior art turbine engines or other devices where abladed rotating wheel is attached to a rotating axle. Implementationsubstantially involves forcing a cooling fluid through channelssubstantially parallel to and rotating with the axle, to emerge throughopenings in proximity of the base of each individual blade of the bladedrotating wheel.

Free Nozzle Wheel

If the cycle pressure ratio of a given OCN engine is too high to beefficiently utilized using a single compressor-driving nozzle wheel(calculated to be in the order of 6:1) a second contra-rotating freenozzle wheel is used. No stationary guide vanes are required between thetwo nozzle wheels. Functionally, a free-nozzle wheel acts analogously toa free turbine in prior art turbine engines. It is important to note,however that an OCN engine free nozzle wheel is significantly moreefficient than a prior art turbine engine free turbine. The greaterefficiency is due to the fact that for reasons analogous to thosediscussed for the compressor driving nozzle wheel of an OCN engine, thenozzle angles of a free nozzle wheel are significantly greater thanthose of the analogous free turbine blades.

In FIG. 7 is depicted a turboshaft embodiment of an OCN engine 106,similar to turbojet OCN engine 40 depicted in FIG. 2. Amongst otherdifferences, in torque section 48 of OCN engine 106 there is afree-nozzle wheel 108 in addition to compressor-driving nozzle wheel 50.As is clear to one skilled in the art, not only is such a design compactand efficient, but is able to handle a cycle pressure ratio of up toabout 24:1 with only two expansion stages.

An advantage of the contra-rotation of the two nozzle wheels, 50 and 108is that gyroscopic forces are reduced. The possibility of reducinggyroscopic forces makes a two-nozzle wheel OCN engine exceptionallyuseful for the propulsion of light aircraft.

Partial Admission

Often a low-power but efficient turbine engine is required. Such enginesrequire a high pressure ratio with a low mass flow having narrow flowpassageways where boundary layer interactions cause a significant lossof efficiency.

An alternative known in the art is to reduce the power output of a largeturbine engine by blocking some of the turbine nozzle vanes in order toreduce flow. Although power output is reduced, efficiency is alsodramatically worsened, due to the drag caused by non-used turbineblades.

In contrast, partial admission is applied to an OCN engine to reducepower without affecting efficiency.

In FIG. 8, a rotating assembly 54 of an OCN engine is depicted where thegap surface area of both compressor wheel 56 and compressor-drivingnozzle wheel 50 are blocked by, for example, attaching a cover so as toblock the space between some of compressor blades 108 and nozzle wheelblades 98 (in FIG. 8, the hatched markings). Although through-flow andpower output is reduced at each stage, the OCN engine continues tofunction at a maximal efficiency.

Practical Embodiments

From the description hereinabove, one skilled in the art sees that theteachings of the present invention can be utilized in making engines formany different purposes. A turbojet embodiment of an OCN engine 40 isdepicted in FIG. 2 and in FIG. 7 a turboshaft embodiment 106 of an OCNengine is depicted. In FIG. 9 a turbofan embodiment 112 of an OCN engineis depicted. In FIG. 10 a turboprop embodiment 114 of an OCN engine isdepicted. Like components of the four embodiments are labeled with likereference numerals. Salient differences between the various embodimentsof an OCN engine are clear to one skilled in the art from study of theappropriate figures.

Amongst other details, it is important to note that OCN turbojet 40depicted in FIG. 2 is equipped with a convergent type exhaust duct 110to maximize thrust.

Amongst other details, it is important to note that OCN turbojet 106depicted in FIG. 7 is equipped with free-nozzle wheel 108 to maximizetorque production through torque shaft 116.

Amongst other details, it is important to note that OCN turbofan 112depicted in FIG. 9 is equipped with a convergent type exhaust duct 110to maximize thrust.

Amongst other details, it is important to note that OCN turboprop 114depicted in FIG. 10 is equipped with free-nozzle wheel 108 to maximizetorque production through torque shaft 116. Gears 118 are used tocombine torque from torque shaft 116 and rotating shaft 52 to drivepropeller shaft 120. As stated above, contra-rotation of the two nozzlewheels, 50 and 108 reduces gyroscopic forces making a two-nozzle wheelOCN engine such as 114 exceptionally useful for the propulsion of lightaircraft.

Efficiency of an OCN engine

The mechanical advantages of an OCN engine over a conventional turbineengine are manifest to one skilled in the art reading the descriptionhereinabove. However, in addition to the reduced number of components,simplicity of components and efficient cooling of these components, thetheoretical thermodynamic efficiency of an OCN turbine engine is greaterthan that of a conventional prior art turbine engine (due to theelimination of stators in the compressor and the turbines) primarilyalong the inlet and exhaust legs of the thermodynamic cycle. A detaileddiscussion of the thermodynamic cycle of an OCN engine is found in theappendix attached hereto.

While the OCN engine has been described with respect to a limited numberof embodiments, it will be appreciated that many variations,modifications and other applications of the OCN engine may be made.

1. An engine, comprising: a. a rotating assembly including a primarycompressor, an inner casing and a compressor-driving nozzle wheel; b. anouter casing, enclosing said rotating assembly; and c. a substantiallyannular flame holder encircling said inner casing within said combustionchamber; so that at least one combustion chamber is defined in the spacebetween said primary compressor, said inner casing, saidcompressor-driving nozzle wheel and said outer casing, characterized inthat said outer does not rotate said rotating assembly.
 2. The engine ofclaim 1, wherein said at least one combustion chamber is substantially asingle annular combustion chamber.
 3. The engine of claim 1, whereinsaid rotating assembly includes a single said flame holder.
 4. Theengine of claim 1, wherein said flame holder is included in saidrotating assembly.
 5. The engine of claim 1, fiber comprising: c. asubstantially tubular element surrounding said inner casing, wherein aleading edge of said tubular element is positioned aft of said primarycompressor so as to divide airflow from said primary compressor into anouter airflow and an inner airflow, wherein said outer airflow isbetween said tubular element and said outer casing and wherein saidinner airflow is between said tubular element and said inner casing 6.The engine of claim 5 wherein through said substantially tubular elementare perforations allowing communication between said inner airflow andsaid outer airflow.
 7. The engine of claim 1 further comprising: c. arotating diffuser between said primary compressor and said combustionchamber.
 8. The engine of claim 7 wherein said rotating diffuserincludes extensions to terminal blades of said primary compressor. 9.The engine of claim 1 wherein said rotating assembly further includes atleast one fuel injector.
 10. An engine comprising: a. a combustionchamber having an axis; and b. a combustion chamber compressor, coaxialwith and radially inwards from said combustion chamber configured tocounteract axial backflow in said combustion chamber.
 11. The engine ofclaim 10 wherein said combustion chamber compressor includes: c. atleast two combustion chamber compressor blades arrayed about said axisof said combustion chamber in at least one circle; and d. asubstantially tubular combustion chamber compressor body encasing saidcombustion chamber compressor blades.
 12. The engine of claim 10 furthercomprising: c. a rotating combustion chamber inner casing coaxial withsaid combustion chamber; d. at least two combustion chamber compressorblades rigidly attached to said rotating combustion chamber inner casingand arrayed about said axis of said combustion chamber in at least onecircle; and e. a substantially tubular combustion chamber compressorbody encasing said combustion chamber compressor blades.
 13. In anengine having a combustion chamber wherein a mixture of fuel and air isburned, a method of reducing NO_(x) emissions comprising: a. making acombustible mixture by combining exhaust, fuel and air in a first regionof the engine; b. establishing an airflow vortex, within the combustionchamber, that creates a higher static pressure in a second region of theengine than in said first region of the engine; and c. burning saidcombustible mixture in the combustion chamber; wherein said exhaust istaken from said second region of the engine by said higher staticpressure in said second region.
 14. A method of cooling a blade of abladed rotating wheel attached to the terminal end of a rotating axisthrough a blade base, comprising: a. providing at least onesubstantially annular axial channel rotating with the rotating axis,said at least one channel having an inlet and an outlet; b. feeding acooling fluid into said at least one channel through said inlet; and c.directing cooling fluid emerging from said channel through said outletat an outer suit of the blade base.
 15. The method of claim 14 furthercomprising: d. increasing the pressure of said cooling fluid emergingthrough said outlet using a pressure-increasing device positioned insidesaid at least one channel.
 16. The method of claim 14 wherein saidbladed rotating wheel is a nozzle wheel and wherein said blade is anozzle wheel blade.
 17. The method of claim 14 wherein said bladedrotating wheel is a turbine wheel and wherein said blade is a turbineblade.
 18. An engine, comprising: a. a rotating assembly including aprimary compressor, an inner casing and a compressor-driving nozzlewheel; b. an outer casing, enclosing said rotating assembly; and c. acombustion chamber compressor in said combustion chamber; so that atleast one combustion chamber is defined in the space between saidprimary compressor, said inner casing, said compressor-driving nozzlewheel and said outer casing, characterized in that said outer casingdoes not rotate with said rotating assembly;
 19. The engine of claim 18,wherein said combustion chamber compressor comprises a plurality ofcombustion chamber compressor blades attached to said inner casing. 20.An engine, comprising: a. a rotating assembly including a primarycompressor, an inner casing and a compressor-driving nozzle wheel; andb. an outer casing, enclosing said rotating assembly; so that at leastone combustion chamber is defined in the space between said primarycompressor, said inner casing, said compressor-driving nozzle wheel andsaid outer casing, said compressor-driving nozzle wheel including aplurality of blades that define between them a corresponding pluralityof nozzles, each said nozzle having a convergent-divergent shape.
 21. Anengine, comprising: a. a rotating assembly including a primarycompressor, an inner casing and a compressor-driving nozzle wheel; andb. an outer casing, enclosing said rotating assembly; so that at leastone combustion chamber is defined in the space between said primarycompressor, said inner casing said compressor-driving nozzle wheel andsaid outer casing, the engine further comprising: c. a free nozzle wheelaft of said compressor-driving nozzle wheel; and wherein the enginelacks stator guide vanes between said nozzle wheels.
 22. The engine ofclaim 21, wherein said free nozzle wheel includes a plurality of bladesthat define between them a corresponding plurality of nozzles, saidblades being positioned so that gas jets that emerge from said nozzlesemerge at an angle of at least about 82 degrees from parallel with arotational axis of said rotating assembly.
 23. An engine, comprising: a.a rotating assembly including a primary compressor, an inner casing anda compressor-driving nozzle wheel; and b. an outer casing, enclosingsaid rotating assembly; so that at least one combustion chamber isdefined in the space between said primary compressor, said inner casing,said compressor-driven nozzle wheel and said outer casing, wherein atleast one of said primary compressor and said nozzle wheel is partlyblocked.